Design, Synthesis, and Biological Evaluation of Pyrrole-2-carboxamide Derivatives as Mycobacterial Membrane Protein Large 3 Inhibitors for Treating Drug-Resistant Tuberculosis

In this work, pyrrole-2-carboxamides were designed with a structure-guided strategy based on the crystal structure of MmpL3 and a pharmacophore model. The structure-activity relationship studies revealed that attaching phenyl and pyridyl groups with electron-withdrawing substituents to the pyrrole ring and attaching bulky substituents to the carboxamide greatly improved anti-TB activity. Most compounds showed potent anti TB activity (MIC < 0.016 mu g/mL) and low cytotoxicity (IC50 > 64 mu g/mL). Compound 32 displayed excellent activity against drug resistant tuberculosis, good microsomal stability, almost no inhibition of the hERG K+ channel, and good in vivo efficacy. Furthermore, the target of the pyrrole-2-carboxamides was identified by measuring their potency against M. smegmatis expressing wild-type and mutated variants of the mmpL3 gene from M. tuberculosis (mmpL3tb) and determining their effect on mycolic acid biosynthesis using a [C-14] acetate metabolic labeling assay. The present study provides new MmpL3 inhibitors that are promising anti-TB agents.

Automated summary

In this study, pyrrole-2-carboxamides were designed and synthesized as potential anti-TB agents based on the crystal structure of MmpL3 and a pharmacophore model. Structure-activity relationship studies revealed the importance of specific substituents on the pyrrole ring and carboxamide moiety in enhancing the anti-TB activity. One compound showed excellent activity against drug-resistant tuberculosis and exhibited promising pharmacological properties. The target of these pyrrole-2-carboxamides was identified through functional assays. This study provides new MmpL3 inhibitors that may serve as effective treatments for tuberculosis.